Category: Breeding

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Orange revolution

Sweetpotatoes come in different colors and tastes (and sizes). The “yams” eaten in the United States are sweet and have orange and moist flesh. The staple of parts of Africa and the Pacific (and pig feed in China), is typically white-fleshed and not very sweet nor moist (notwithstanding variations like this purple variety.)

Anyway, the orange fleshed sweetpotato is stacked with beta-carotene, the stuff you need to eat for your body to make vitamin A. Many poor people have vitamin A deficiencies, which leads to stunted growth and blindness. So why don’t the poor sweetpotato eaters eat orange fleshed varieties? In part because they simply do not have them, or know about their health benefits. In part because they do not grow well in Africa (decimated by pests and diseases). And also because they do not taste right: too sweet for a staple.

The International Potato Center and partners have been trying to fix all that. Now they have made a nice video about getting orange-fleshed sweetpotatoes into the food-chain in Mozambique. The orange revolution:

https://vimeo.com/2278794

I wonder if they also promote mixing more sweetpotato leaves into the diet — even of white fleshed varieties. The leaves are a very good source of micro-nutrients, including beta-carotene! More fodder for the biofortification discussion.

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Nibbles: Early diet, Rice, Veggies, Barley, Research, Taiwan, Coffee trade

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Nibbles: String, Lake District, Apples, Biochar, Display, Firs, Sweet potato, Rice, Bison

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Induced mutations? Nein danke.

We briefly nibbled SciDev.Net’s take on a press release from the International Atomic Energy Authority, advocating “Nuclear Science for Food Security”. It’s an old story; bombard seeds with radioactivity to induce more mutations, from which breeders can select wonderful new varieties. But as a correspondent reminds us:

There’s really nothing inherently wrong with it. Because it’s a totally random, “shotgun” approach to generating new variations, it lacks the benefits of natural selection to sort out not only what’s viable, but also what’s somehow well-adapted to growing in the environment and have other desirable traits.

Radio-induced mutagenesis was a popular technique decades ago, and some improved varieties were produced as a result. But I think that a much more logical approach would be to more fully assess and exploit the vast amount of extant diversity currently languishing unstudied in genebanks and farmers’ field, material that has already passed through the filter of many centuries, if not millennia, of natural and human selection. Radio-induced mutation is really just a shot in the dark. Better to focus more attention on the existing crop diversity that has yet to be exhaustively collected, characterized or evaluated, before resorting to such an aleatory approach.

Do you agree? Is inducing extra mutations — by chemistry, radioactivity, whatever — a good way to generate more diversity for breeders (and farmers?) to select from. Or should we focus on understanding the diversity we already have? It isn’t binary, of course, but I wonder where the balance should be?

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Go forth and grow halophytes

That seems to be the plea Jelte Rozema and Timothy Flowers make in a Science paper that’s just out. ((It’s behind a paywall, but you can read other people’s take on it at Mongabay and Wired.)) But, frankly, I found the paper disappointing, not least because it is short on clear recommendations. For example, what is one to make of this?

Because salt resistance has already evolved in halophytes, domestication of these plants is an approach that should be considered. However, as occurred with traditional crops such as rice, wheat, corn, and potatoes, domestication of wild halophytic plant species is needed to convert them into viable crops with high yields. Such a process can begin by screening collections for the most productive genotypes.

Are they telling us that domestication of new species is a more profitable approach than trying to breed salinity-tolerance into existing crops? I think so, in which case it would be an interesting view, but I’m not altogether sure that’s in fact the point they’re making. It could have been better phrased. I mean those first two sentences could be summarized as

Domestication of halophytes should be considered. However, domestication of wild halophytes is needed.

Not sure how the editors at Science let that one by. There was also no explicit reference in the paper to the International Centre for Biosaline Agriculture and its genebank. Or to the possible role of crop wild relatives in breeding for salinity tolerance. All around, an opportunity missed.